Retractable beam splitter for microscope

ABSTRACT

Systems and methods are provided for illuminating a surface to be observed microscopically using a retractable beamsplitter. The retractable beamsplitter allows the use of coaxial illumination when the beamsplitter is positioned in the operator&#39;s line of sight. The retractable beamsplitter allows the use of non-coaxial illumination without reducing the amount of illumination that reaches the operator when the beamsplitter is retracted from the operator&#39;s line of sight. As a result a single system can be used effectively to provide various types of illumination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No.12/267,380, filed on Nov. 7, 2008.

FIELD OF THE DISCLOSURE

The present disclosure is in the field of microscopes.

BACKGROUND

This disclosure refers to various outside documents to aid the reader inunderstanding the embodiments of the processes, machines, manufactures,compositions of matter, and other teachings of the present disclosure;to enable those of ordinary skill in the art to practice the embodimentsof the processes, machines, manufactures, compositions of matter, andother teachings of the present disclosure; and to allow one of ordinaryskill in the art to understand the metes and bounds of the embodimentsof the processes, machines, manufactures, compositions of matter, andother teachings of the present disclosure. No admission is made that anysuch document meets any legal definition of “prior art” in any country,and the Applicants reserve the right to demonstrate that any suchdocument meets or fails to meet any legal definition of “prior art” inany country. All such documents are incorporated by reference herein sofar as is necessary to enable those of ordinary skill in the art topractice the embodiments of the processes, machines, manufactures,compositions of matter, and other teachings of the present disclosure;and to allow one of ordinary skill in the art to understand the metesand bounds of the embodiments of the processes, machines, manufactures,compositions of matter, and other teachings of the present disclosure.

In the surgical setting, there have been a number of differentmicroscopes designed and sold for ophthalmic surgery. Presently thereare no microscopes that deliver two collimated light beams instereoscopic to the subject surface, e.g., the tissue under examinationin a surgical procedure.

Until now microscopes have delivered to the subject surface (1) one ormore uncollimated light beams from the objective lens or (2) a singleuncollimated light beam below the objective. Routing a parallel lightbeam through the objective lens transmits a light beam which is notcollimated. The illumination system, described in U.S. Pat. No.4,779,968 delivered a single uncollimated light beam from a single lightsource to the subject surface through objective lens (shown as 1 or 1a),wherein FIGS. 1 and 3 of U.S. Pat. No. 4,779,968 depict the beam to thesubject surface passing through an objective lens which is uncollimated.Another illumination system believed to be from the Zeiss Lumeramicroscope delivered two focused (uncollimated) beams to the subjectsurface through the objective lens. Another illumination system from theMoller EOS 900 microscope delivered two focused (uncollimated) lightbeams through the objective lens to the subject surface.

U.S. patent publication 2010/0118549, published May 13, 2010, describesan invention directed toward cataract surgery in which the microscopelight reflects from the retina to produce a red reflex, in essence abacklighting of the lens in cataract surgery.

Illumination in retinal surgery is different from that in cataractsurgery. In retinal surgery the microscope is equipped with a device formagnifying the retina so that the surgeon sees a large view of theoperative site. However, the illumination of the surgical microscope forcataract surgery is not used in retinal surgery. In retinal surgery, asmall fiber-optic pic about 1 mm in diameter is inserted through thesclera and into the vitreous body for direct illumination of the retinalsurface. The surgeon holds this fiber-optic pic such that light exitingthe tip of the fiber-optic pic is directed toward the retinal tissue onwhich the operating instruments are utilized.

SUMMARY

Microscopes are used in many different fields. The systems of thepresent disclosure can be used in any field but are especially useful insurgical settings or any other application in which highly threedimensional objects require magnification, particularly those partiallyoccluded by an enclosure. An example of this is ophthalmic surgery

The illumination system of the present disclosure allows delivery of twocollimated light beams to the subject surface which at least partiallyoverlap, producing stereoscopic illumination. Additionally, anindependent system of illumination may be provided at an angle obliqueto the stereoscopic system. Either system can be used together orseparately.

As defined herein and unless otherwise stated, (a) “collimated light”means light rays from any light source which are partially parallelinstead of converging or diverging; and (b) “collimation” means theprocess of arranging converging or diverging light beams so that theyare at least partially parallel. If the light source for eachstereoscopic beam was truly a point source there would be little overlapof the beams on the subject surface. With a white light source the focallength of the lens varies with wavelength. An ideally collimated beamwould result from a monochromatic point source located at the focalpoint of the condenser lens. The larger the light source, however, themore other effects occur. Light from one side of the bulb, for example,enters the condenser lens at a different point than light from thebulb's other side and therefore they behave differently as they exit thelens. Light that lies directly on the optical axis of the lens iscollimated but the off axis light creates some divergence in the beams.

Certain embodiments of the illumination system incorporate a 50%/50%beamsplitter plate. The beamsplitter plate facilitates red reflexenhancement during cataract surgery on the lens, but is not necessaryfor retinal surgery. In fact, its presence can reduce 50% of the lightreturning from the surgical site to the surgeon's eyes. It is thereforedesirable to remove the beamsplitter plate from the optical system forretinal surgery. In certain embodiments of the system this isaccomplished by allowing the beamsplitter plate to be removed from thelight beam path, thus allowing 100% of the reflected light from theretina to enter the optical system of the surgical microscope.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view from the top of an embodiment of the illuminationsystem showing the stereoscopic illumination system and the obliqueillumination system. The lines with arrows represent the centers of thelight beams from their source until they reflect against thebeamsplitter (for stereoscopic) and against the full mirror (foroblique).

FIG. 2 is a side schematic view of one side of the embodiment of thestereoscopic illumination system. It shows a single collimated lightbeam illuminating the subject surface, in this instance an eye, andlight from the eye's red reflex traveling through the objective lenstoward the binoculars.

FIG. 3 is a side schematic view of an embodiment of the obliqueillumination system, in which the light is offset at an angle oblique tothe stereoscopic illumination system. It shows a light beam illuminatingthe subject surface, in this instance an eye, and light from the eye'sred reflex traveling through the objective lens toward the binoculars.

FIG. 4 is a side view of an embodiment of the system as a detachablemodule for an existing microscope, including a side schematic view ofthe stereoscopic illumination system and how the light beam illuminatesthe subject surface. It shows a collimated light beam illuminating thesubject surface, in this instance an eye, and light from the eye's redreflex traveling through the objective lens toward the binoculars.

FIG. 4 a is a side view of an embodiment of the illumination system as adetachable module for an existing microscope, including a side schematicview of the oblique illumination system and how the light beamilluminates the subject surface. It shows a light beam illuminating thesubject surface, in this instance an eye, and light from the eye's redreflex traveling through the objective lens toward the binoculars.

FIG. 5 is a side view of an embodiment of the illumination system as amodule attached to an existing microscope, including a side schematicview of the stereoscopic illumination system and how the light beamilluminates the subject surface. It shows a collimated light beamilluminating the subject surface, in this instance an eye, and lightfrom the red reflex traveling through the objective lens toward thebinoculars.

FIG. 5 a is a side view of an embodiment of the illumination system as amodule attached to an existing microscope, including a side schematicview of the oblique illumination system and how the light beamilluminates the subject surface. It shows a light beam illuminating thesubject surface, in this instance an eye, and light from the red reflextraveling through the objective lens toward the binoculars.

FIG. 6 is a 3 dimensional cutaway of an embodiment of the illuminationsystem including the stereoscopic and the oblique illumination systems,the centers of the light beams, and the patterns of illumination on thesubject surface.

FIG. 7 depicts an embodiment of the illumination system with rheostats,for independent control of each illumination source, and theirconnections to an external power source.

FIGS. 8 and 8 a depict the illumination system described in U.S. Pat.No. 4,779,968.

FIG. 9 depicts an illumination system believed to be the Zeiss Lumeramicroscope delivering two focused (uncollimated) beams to the subjectsurface through the objective lens.

FIG. 10 depicts an illumination system from the Moller EOS 900microscope delivering two focused (uncollimated) light beams through theobjective lens to the subject surface.

FIG. 11 is a side view of the microscope with disengagement of theretractable beamsplitter plate 31 for retinal surgery.

DETAILED DESCRIPTION

An illumination system for a microscope is provided, the illuminationsystem being below the objective lens 11 a of the microscope. Theillumination system contains two illumination sub-systems, the firstbeing the stereoscopic sub-system which delivers two beams of collimatedlight (as defined herein) to the subject surface 16. These two beams ofcollimated light overlap on the subject surface 16 at least partially.The advantage of the stereoscopic collimated light is a better threedimensional view than produced by prior art illumination systems undersimilar circumstances. Compared to uncollimated light, deliveringcollimated light into a partially occluded opening allows a (a) greaterquantity of light and (b) more direct light. The at least partialoverlap of the collimated light allows the user viewing throughbinoculars 22 to view the subject surface 16 optimally with stereopsis.An additional illumination sub-system at an angle oblique to thestereoscopic sub-system is also provided, but the light for the obliquesystem need not be collimated.

A particular embodiment produces collimated light beams for each of thetwo stereoscopic light beams by passing light through an asphericcondensing lens 4 and then through a plano-convex lens positioned at theappropriate focal plane. The collimation can be accomplished at multiplepoints between the light source 5 and the subject surface 16 (e.g.,before or after filtering, or before or after the beam is split).

The system can be built into an entire microscope or can be constructedas a module fitting onto an existing microscope. If constructed as amodule, the module includes an objective lens 11 a that replaces theobjective lens of the microscope. Situated below the included objectivelens 11 a of the module type or of the objective lens 11 a of thebuilt-in type, are illumination components for directing light to thesubject surface 16. The construction of the microscope may be alteredsubstantially without affecting the illumination system.

In a further embodiment, one light source 5 produces two beams of lightfor the stereoscopic system which are directed by the following elementsto the subject surface 16 as two collimated light beams. In anotherembodiment, the two collimated light beams are produced by two lightsources, one for each light beam. The illumination components of thelight source 5 for the stereoscopic system and the light source 7 forthe oblique system are located inside the module or existing microscopeand are separated by an opaque barrier 6. A beam from the stereoscopiclight source 5 is collected by two condensing lenses 4 that gather andconcentrate the light.

In another embodiment, each gathered and concentrated light beam passingthrough a condensing lens 4 is transmitted through an infrared filter 3then through an ultraviolent filter 2 and then through a collimatinglens 8. In one embodiment, a collimating lens 8 is a double convex lens(i.e., with a curved surface on both sides) with a positive focal lengthwhich, when used in conjunction with an upstream aspheric condensinglens 4 and positioned at the appropriate focal plane, producescollimated light.

In some embodiments, however, one light source 5 for the stereoscopicsystem is used to produce two beams of light in the following manner. Abeam from each of two sides of the light source 5 is directed through aDove prism 1 (bending light twice for a total of 180°) before reachingthe collimating lens 8. After passing through the collimating lenses 8,each collimated light beam is then refracted by a 90° prism 10. Eachcolumn of collimated light exits its 90° prism 10 parallel to the otherso that each strikes a beamsplitter 12 at an angle so that a portion ofeach column of collimated light is reflected downward toward the subjectsurface 16.

These columns of collimated light reflected from the beamsplitter 12downward to the subject surface 16 overlap each other at least partiallyat the stereoscopic illumination overlap 27 as dictated by the focallength of the included objective lens 11 a. The portion of light fromthe collimated beams of light passing through the beamsplitter 12 isabsorbed by an anti-reflective light absorber 13. In a preferredembodiment, the beamsplitter 12 splits the light in half, one halfreflected to the subject surface 16 and the other half passes throughthe beamsplitter 12 to the anti-reflective light absorber 13. Thebeamsplitter 12 can be a half mirror or a mirror partially reflective inanother fraction (e.g., three quarters reflective). The function of thebeamsplitter 12 is to allow light to pass upward from the subjectsurface 16 to the binoculars 22 for the user. The collimated light beamsare coaxial with the light transmitted to the binoculars 22. A planoglass cover 15 encloses the bottom portion of the module to protect thecomponents from contaminants.

In some embodiments of the illumination system three beams of light arerequired, but they can be achieved in various ways. One way would be touse three light sources with each one having its own set of condensing 4and collimating lenses 8. Another way would be to use two light sources,like the model depicted herein. This would utilize light emitting fromtwo sides of one bulb for the stereo paths, and the second light source7 for the oblique path. Another way would be to use one source. Lightcould be gathered from three sides of the bulb, condensed and collimatedseparately to form the three needed beams, or light could be gatheredand then optically split into separate beams later on down the pathway.The significant advantage to using more than one light source, is theability to adjust the illumination ratio between stereo and obliquelight for optimal viewing. Using one source and having the ability toadjust light ratios would require mechanical shutters to block lightaccordingly. Another variance to the light source is to use fiber-opticlight source. This merely removes the actual bulbs from the closeproximity of the system and places them in a more remote location. Theadvantages of this are the ability to use higher power light sourcesthat would not realistically fit in the module, heat generated by thebulbs being removed from proximity of the surgical procedure, and noiseand air from the internal fan 17 also being removed to the remote site.One disadvantage with a fiber-optic system is light loss through thefiber-optic cable. Another variance for light sourcing is an LED (LightEmitting Diode) light source. It is also possible to have anycombination of LED, bulb, and fiber-optic sources all in one system.

A light source for the oblique system 7 is located so that light fromsaid the second light source is directed through a condensing lens 4that gathers and concentrates the light from the light source 7. Thegathered and concentrated light from the condensing lens 4 istransmitted through an infrared filter 3, and an ultraviolent filter 2to a collecting lens 8 a which collects diverging light from thecondensing lens 4. The light passes through the collecting lens 8 a andis reflected downward toward the subject surface 16 at an angle so thatoblique illumination 28 of the subject surface 16 is accomplished. Theoblique illumination 28 covers the entire visual field for both eyes ofthe user, assuming the objective is at a middle range or higher. Theoblique illumination 28 can be reduced by an adjustable mechanicalaperture 25 so that the illumination is centered in a smaller area ofthe subject surface 16, for instance the iris of an eye only, toeliminate glare to the user from light reflecting from the sclera of theeye.

The infrared filter 3 and ultraviolet filter 2 can be placed at anyconvenient position in the pathway between the light sources 5, 7 andthe subject surface 16.

Rheostats 26 may control the intensity of the two light sources 5, 7 tocontrol the amount of light projected to the subject surface 16.

A cooling fan 17 may be mounted in close proximity to the bulb tray 19or other light sources in the illumination system.

The housing 18 of the modular component may contain a fitting forconnection to an existing microscope. This fitting may attach at theexisting microscope's objective lens receptacle 11 after the existingmicroscope's objective lens is removed. This fitting locks the modulehousing 18 in place in the existing microscope's objective lensreceptacle 11. A particular embodiment of this fitting is an attachmentring 20 which screws or otherwise mounts onto the existing microscope.

For the full microscope containing the system, the binoculars 22 are incommunication with zoom optics 23 which are housed in the microscopebody 21 and are in communication with the objective lens 11 a. There isa focus drive housing 24.

The built-in system may be completely enclosed in the body of themicroscope below the zoom system and the objective lens 11 a.

Ancillary optics, such as mirrors and prisms, are used to refract thelight so that the projected beams exit the system at proper angles. Theycould also be used to split a single light beam into two light beams.This could be done if only one light source was being used, or if afiber-optic system was used and the incoming beam needed to be convertedto two or three beams. This placement of the ancillary optics for lightredirection or splitting along the pathway is irrelevant to the functionas long as the beams are directed to the proper locations, but keepingin mind losses that occur at each light interface.

There are numerous combinations that could be achieved using one or moreof the same or different light sources, mirrors and prisms for directinglight around inside the system, using prisms to split beams at any pointalong the light pathway if there are not enough beams from lightsources, using or not using a mechanical shutter for illuminationintensity control, placement of the ultraviolet 2 and infrared 3filters, and even the direction and angle at which the oblique lightilluminates the field. Ultimately, these variances if done properly, allresult in two collimated stereo illumination beams hitting thebeamsplitter 12 set at a forty-five degree angle in the direct path ofthe optical viewing pathways of a microscope, and a third obliqueillumination beam hitting the subject surface 16 at some offset anglewith the ability to control the levels and/or ratios of saidillumination.

One embodiment directs illumination light rays onto the patient from onelight source, but with three illumination pathways—the two co-axial zerodegree pathways, and one oblique eight degree pathway. The two zerodegree pathways are directed down to the patient via a beamsplitterplate glass 12 directly in-line with the stereo microscope opticalpathways, creating the true dual co-axial illumination. This providesoptimal red reflex or retinal reflex primarily for cataract surgery, butin other surgical settings the bright full red-reflex is not desired. Inone embodiment of the system, the surgeon has the ability then to turnoff, via shutter, the zero degree co-axial illumination pathways. Atthis point the surgeon is solely utilizing the eight degree illuminationfor surgery. When the microscope is being used in this state, thebeamsplitter 12 is no longer needed, as there is no zero degreeillumination. To maximize light transfer through the system, thebeamsplitter 12 is moved out, or disengaged, from the stereo microscopeoptical pathways. Then when the zero degree co-axial illumination isrequired again, the user can re-engage the beamsplitter 12 plate andzero degree co-axial illumination.

Retinal surgery requires the use of a surgical microscope. Themicroscope is equipped with a device for magnifying the retina so thatthe surgeon sees a large view of the operative site. However, the normalillumination of the surgical microscope is not used in retinal surgery.A small fiberoptic pic about 1 mm in diameter can be inserted throughthe sclera and into the vitreous body for direct illumination of theretinal surface. The surgeon holds this fiberoptic pic such that lightexiting the tip of the fiberoptic pic is directed toward the retinaltissue on which the operating instruments are utilized. Since the normalillumination of the microscope is not utilized and is in fact turnedoff, and since only the relatively low illumination from the fiberopticpic illuminating the retinal surface is seen by the surgeon, it is tothe surgeon's advantage to have an optical system that does notsignificantly decrease the light from the retina. It can therefore bedesirable, in one embodiment, to retract the beamsplitter plate from theoptical system for retinal surgery. The present invention accomplishesthis goal by allowing the beamsplitter plate to be rotated out of thelight beam path, thus allowing 100% of the reflected light from theretina to enter the optical system of the surgical microscope and betransmitted to the user. Thus, when co-axial illumination is notdesired, a retractable beamsplitter plate 31 is disengaged to slightlybeyond a vertical position. In this position there is no light loss fromhaving the retractable beamsplitter plate 31 incident to the light rays2 entering the microscope system. By disengaging the retractablebeamsplitter plate 31 a 50% increase in light transfer efficiency can beachieved, thus allowing more light to reach the surgeon. Thebeamsplitter is thus retractable, and in this way the same microscopecan be used, on the one hand, in cataract and other surgery using theillumination system and with the retractable beamsplitter engaged, onthe other hand, in retinal and other surgery without using theillumination system and with the retractable beamsplitter disengaged.

CONCLUSION

It is to be understood that any given elements of the disclosedembodiments of the invention may be embodied in a single structure, asingle step, a single substance, or the like. Similarly, a given elementof the disclosed embodiments may be embodied in multiple structures,steps, substances, or the like. The foregoing description illustratesand describes the processes, machines, manufactures, compositions ofmatter, and other teachings of the present disclosure. Additionally, thedisclosure shows and describes only certain embodiments of theprocesses, machines, manufactures, compositions of matter, and otherteachings disclosed, but, as mentioned above, it is to be understoodthat the teachings of the present disclosure are capable of use invarious other combinations, modifications, and environments and iscapable of changes or modifications within the scope of the teachings asexpressed herein, commensurate with the skill and/or knowledge of aperson having ordinary skill in the relevant art. The embodimentsdescribed hereinabove are further intended to explain certain best modesknown of practicing the processes, machines, manufactures, compositionsof matter, and other teachings of the present disclosure and to enableothers skilled in the art to utilize the teachings of the presentdisclosure in such, or other, embodiments and with the variousmodifications required by the particular applications or uses.Accordingly, the processes, machines, manufactures, compositions ofmatter, and other teachings of the present disclosure are not intendedto limit the exact embodiments and examples disclosed herein.

1. An illumination system for a microscope which delivers two collimatedlight beams to a subject surface where the two collimated light beams atleast partially overlap, said system comprising a retractablebeamsplitter in the line of sight of the microscope capable of beingpositioned to reflect a portion of the two collimated light beams to asubject surface such that the two collimated light beams overlappartially at the subject surface, and capable of being retracted outsideof the line of sight of the microscope when the illumination system isnot in use.
 2. The system of claim 1, further comprising a light beamdelivered to the subject surface offset at an angle oblique to the axisof the two collimated light beams.
 3. The system of claim 1, wherein thetwo collimated light beams each have a center which is substantiallyparallel to the other and substantially in the same plane.
 4. The systemof claim 1, further comprising a third light beam which is transmittedto a front of the target and has a center having an axis which is offsetat an angle oblique to the plane created by axes of the centers of thetwo collimated light beams.
 5. The system of claim 4 wherein the thirdlight beam illuminates the entire visual field.
 6. The system of claim 2further comprising means for adjusting the ratio of the intensity of (a)the light of the two collimated light beams; to (b) the light beamdelivered to the subject surface which is offset at an angle oblique tothe axis of the two collimated light beams.
 7. The system of claim 1wherein the two collimated light beams are at an angle of incidence of 0degrees to the subject surface.
 8. The system of claim 1 wherein the twocollimated light beams are below an objective lens.
 9. The system ofclaim 1 wherein the two collimated light beams do not pass through theobjective lens.
 10. The system of claim 1 wherein the two collimatedlight beams are below the beamsplitter, and wherein the two collimatedlight beams have substantially the same axes as a pair of observationbeams above the objective lens.
 11. An illumination system for amicroscope, comprising: a. at least one light source producing twouncollimated light beams; b. two condensing lenses through which each ofthe two uncollimated light beams passes separately to two collimatinglenses; c. wherein the two collimating lenses collimate each of the twouncollimated light beams separately and pass the two collimated lightbeams to a retractable beamsplitter; d. wherein the retractablebeamsplitter is capable of being positioned to reflect a portion of thetwo collimated light beams to a subject surface such that the twocollimated light beams overlap partially at the subject surface; and e.wherein the retractable beamsplitter is capable of being retractedoutside of the line of sight of the microscope when the illuminationsystem is not in use.
 12. The system of claim 11 wherein at least oneuncollimated light beam is delivered to the subject surface which isoffset at an angle oblique to the axis of the two collimated lightbeams.
 13. The system of claim 11 comprising an anti-reflective lightabsorber behind the beamsplitter.
 14. A method of providing illuminationfor the microscopic observation of a subject surface comprisingdelivering two at least partially overlapping collimated light beams tothe subject surface, and reflecting a portion of the two collimatedlight beams against a retractable beamsplitter to the target such thatthe two collimated light beams overlap partially at the target.
 15. Amethod of providing illumination for the microscopic observation of asubject surface, comprising: a. producing two uncollimated light beams;b. passing each of the two uncollimated light beams separately throughtwo condensing lenses and through to two collimating lenses; c.collimating each of the two uncollimated light beams separately to formtwo collimated light beams; d. passing the two collimated light beamsthrough a retractable beamsplitter; and e. reflecting a portion of thetwo collimated light beams against the retractable beamsplitter to thesubject surface such that the two collimated light beams overlappartially at the target.
 16. A method of providing illumination for themicroscopic observation of a subject surface comprising illuminating thetarget with any one of the systems of claims 1-13. 17-20. (canceled)